I would highly advice to take the GL videos lessons end to end to have your gaps cleared.
All companies will have a balance in functional currency in one ledger. Anything else if you want then we are talking more than one ledger.
When converting journals you must supply one exchange rate at the time of data entry for all journal lines. You can use multipel journals if you wish to use different rates and place the different in an adjustment account. But this approach does not look healthy. Differnet rates are used in translation, not in conversion.